The present invention relates to a combination meter system of a vehicle particularly for improving the precision of various meters or gauges and reducing construction cost by sharing a drive circuit.
An instrument panel of a vehicle is equipped with various gauges such as speed meter, tachometer and the like, which are arranged as a combination meter system in front of a driver sitting on a driver's seat. In a conventional system, independent meters or gauges are merely concentrated in one portion and share only a power source and an earth. An electric power is supplied to a fuel sensor, a temperature sensor of a coolant, a voltage sensor of an alternator to thereby drive a fuel gauge, a temperature gauge, a voltage gauge, respectively.
Driving speed of the vehicle is detected by converting a frequency of a signal output from a speed sensor mounted on an output shaft of a transmission to a corresponding voltage, and by supplying the converted voltage to a gauge as a speed meter through a voltage distribution circuit and an amplifier to drive the gauge.
The Japanese Patent Laid-open Publication No. 53-120016 discloses a combination meter system described above. In such a prior art, there is merely shown a combination meter system in which respectively independent gauges are merely aggregated and share only the power source and the earth. In addition, the respective gauges are not provided with self-adjusting functions, resulting in inferior accuracy and lacking uniformity of qualities of products.